Let me explain a few things to you.
First of all, your impression of a sound system is overly simplified. There are many components between the microphone and the sound console, so thre are many places where the problem could lie, either in an individual component or the connecting cables.
Therefore, the way to troubleshoot a problem is to gradually eliminate the possible causes, beginning with the most likely cause and proceeding from there.
In this case, it was obvious that the singer could hear himself through the stage monitors, eliminating 1 possible cause: Microphone not turned on [yes this happens occasionally]. This also indicated that the signal was arriving at the monitor console correctly. Therefore, the problem had to be somewhere in the signal path between the splitter, which takes the single signal from the microphone and sends it to both the monitor console and the front of house console, and the front of house console itself.
Since it was obvious the second the guy opened his mouth that something was wrong, the first step was to look at the vocal channel on the FOH console to be sure everything was turned on, which it was. So the engineer ran back behind the stage where the splitter and other components are located, to check those. That's why there wasn't anyone behind the board when you went there to insert yourself into the situation...he was already well on his way to fixing the problem. Let me assure you that the last thing ANYBODY who is trying to solve ANY problem in a crunch situation needs is somebody interrupting their train of thought to tell them what they already know.
It turned out the components in the backstage area were fine, narrowing the possible causes still further to the front of house area, where in addition to the sound console there are a number of effects and equalization components that could have been involved.
As it turned out it was one cable that went bad, preventing the signal from reaching the sound console. Sometimes this happens, and there's not a damn thing you can do about it. Everything works fine at soundcheck, and then during the show something doesn't. Guess what? Shit happens.
Contrary to your opinion, the professional thing to do is not to stop the show, but to correct the problem as quickly as possible as the show continues. It's also easier to fix a problem while it is actually occurring rather than stopping and trying to recreate it. This particular problem was repaired pretty quickly considering how many things could have been causing it, and how many potential obstacles there are in the signal path.
Regarding the other issues you mention, it's purely bad luck that the bass rig blew up, and there's nothing the sound engineer can do about that from behind the sound board. If you weren't so busy being pissed off, you might have noticed our stage tech assisting the bass player with his amp, and then rewiring the bass to bypass the amp when it became apparent that it had blown up. Sometimes amps blow, and that's just the way it goes. The only thing you can do is deal with it on the spot.
The guys in the Walkmen have been performing musicians for well over 10 years, and they know that sometimes unforeseen problems occur during shows. That wasn't the first time they've had technical problems during a show and they know it won't be the last. Far from becoming panicked or disheartened, they recovered well and went on to give us a fine show, even with the additional bass amp distraction. The only "heart that had left the building" was yours.
The bottom line here is that live performances are not an exact science. They are a spontaneous, in-the-moment creation with many variables that affect the whole. Sometimes technical problems occur and need to be dealt with. Other times a band member may turn their amp up so loud that it drowns out the other players and/or the vocals, which the sound engineer is powerless to fix because the volume is coming from the stage not through the sound console. Sometimes the singer grips the microphone the wrong way, muffling their own vocals, which the engineer is also powerless to correct. Other times the band is tired, or ill, or not getting along, or just having a bad day, all of which can affect the show. Our technical staff deals with all of these problems, and many more, on a daily basis. Often, the concert-goers don't even know that a major problem occurred and was dealt with in the most professional manner possible. That's a major reason why we have been recognized multiple times by our peers in the music industry as the best club in the country. That's a major reason why bands look forward to coming back here to play. If you have a hard time dealing with the spontaneous nature of live performances, maybe seeing shows just isn't your thing and you would be happier to remain in a more controlled environment, i.e. on your couch, listening to your favorite already recorded music.
